In this 13-part series of articles, The Combustion Institute recognizes the 2021 Distinguished Papers selected from among the scientific papers presented during the 38th International Symposium on Combustion. Congratulations to M. Gauding, M. Bode, D. Denker, Y. Brahami, L. Danaila, and E. Varea for winning the DPA in the Turbulent Flames colloquium.

In their paper, On the combined effect of internal and external intermittency in turbulent non-premixed jet flames, Gauding, Bode, Denker, Brahami, Danaila, and Varea demonstrate the important role turbulent/non-turbulent interface (TNTI) plays in turbulent mixing and subsequent chemical reactions. Furthermore, they demonstrate the ways in which current, conventional theories do not fully describe the process.

In turbulent non-premixed flames, the chemistry-turbulence interaction is crucial in determining the burning rate, but also for the formation of pollutants. In many turbulent non-premixed jet flames, most of the chemical reaction occurs in thin layers at the edge of the flame. The turbulent motion in this area is very complex and characterized by the turbulent/non-turbulent interface (TNTI). The TNTI is a thin layer with a highly corrugated surface that separates the fully developed turbulent core of the jet from the outer irrotational fluid.

Classical theories (for example, Kolmorgorov’s Scaling Theory) for turbulence and turbulent mixing have shown some success but have failed in predicting intermittency. Intermittency describes a process that is characterized by very strong, but very rare fluctuations. Intermittency occurs at different scales; while internal and external intermittency share similar statistical features, their physical origin is very different. In their paper, the researchers successfully developed an improved theory that accounts for both internal and external intermittency.

By developing a mixing model that accounts for the combined effects of internal and external intermittency, engineers’ abilities to predict the turbulence-chemistry interaction in non-premixed flames can be much more accurate. The research was conducted at the French research center “CORIA,” connected to the CNRS and the University of Rouen. The simulations were performed at the research center Jülich in Germany.

Over 1,700 papers were submitted to the 38th International Symposium on Combustion. All papers were categorized into one of 13 colloquia, and then distributed to colloquium coordinators and co-chairs. Each paper was reviewed by at least three qualified individuals from a pool of over 1,000 peer scientific reviewers. Less than 50 percent of the papers submitted are accepted for presentation.

Following the symposium, one paper presented in each colloquium is awarded the distinction of Distinguished Paper. Visit here to view the presentation. The 13 Distinguished Papers undergo committee review for consideration for the Silver Combustion Medal. A paper selected for this honor exemplifies quality, achievement, and significance to advance a field of combustion science, and will be awarded during the 39th International Symposium in Vancouver, Canada.